Plastic block bag with a valve

ABSTRACT

A block bag with a filling valve in which heat seals connect the flap constituting the valve with bottom flap parts such that the shortest distance between the heat seals is equal to or greater than the distance between the side edges formed by the inwardly folded bottom flap parts.

United States Patent [191 [111 3,785,547 De Vries Jan. 15, 1974 [5 PLASTIC BLOCK BAG WITH A VALVE 2,904,241 9/1959 Gorton et a1. 229/625 3,272,093 9/1966 Brockmuller..... 229/625 X [75] Inviemor- R090 Jochum Hendnk De 3,430,844 3/1969 Daniels 229/625 Vl'leS, Hardenberg, Netherlands 3,439,864 4/!969 Kasting et al.. 229/625 x [73] AssigneeZ Industriele ondernenling wavin 3,590,698 7/l97-l De Vrles 93/35 R i g Zwdle FOREIGN PATENTS OR APPLICATIONS SW 7 227,599 5/1963 Austria 229/625 [22] Filed: June 18, 1971 [21] Appl. No; 153,474 Primary Examiner-Davis T. Moorhead AttorneyEdmund M. Jaskiewicz [30] 7 Foreign Application Priority Data June 17, l970 Netherlands 7008908 [57] ABSTRACT 5 us. CL I I I I I I I I 229/62 5 A block bag'with a filling valve in which heat seals in. CI l 31/l'4 connect the flap constituting the valve with bottom [58] Field 229/62 5 flap parts su ch t l 1a t the shortest distance between the heat seals is equal to or greater than the distance be- [56] References Cited tween the side edges formed by the inwardly folded UNITED sTATEs PATENTS flap parts 2,889,979 4 Claims, 5 Drawing Figures 6/l959 Brady 229/625 PLASTIC BLOCK BAG WITH A VALVE The invention relates to a plastic block bag with a filling valve obtained from a tubular foil part by making at least one longitudinal incision at one end of the foil while forming a first corner flap constituting a valve flap between the longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto. The first corner flap is folded outwardly and the bottom flap parts, located beside the longitudinal incision, are folded about a folding line extending in the area next tothe end points of the incisions to form a bottom square with the first corner flap and a second corner flap. The bottom flaps are folded inwardly about a transverse folding line and first sealed joints are formed for connecting the bottom flap parts. Second sealed joints are formed for connecting the first comer flap part, constituting the valve flap, with the bottom flaps. The arrangement is such that the folding edges of the bottom flap parts extend, when the bottom is flat, perpendicularly to the longitudinal edges of the tubular foil in the area between the initial folding line and a line extending, through the end points of the incisions, almost perpendicularly to the longitudinal edges of the tubular foil. Such a block bag has the drawback that the valve flap of the block bag does not close quite satisfactorily in the filled condition of the bag. This is caused by the fact that when the bag is filled the valve flap cannot be stretched and no faultless sealing is ensured.

It is an object of the invention to obviate these difficulties by providing such a plastic block bag that the valve flap, when the bag is filled, is stretched and as a consequence a faultless sealing is ensured.

This object is attained according to the invention in that the shortest distance between the second longitudinal sealed joints is at least equal to the distance between the lateral edges formed by the inwardly folded bottom flap parts.

The invention relates also to a method for manufacturing a plastic block bag with filling valve from a tubular foil by making from one end of the tubular foil at least one longitudinal incision to form a first corner flap, which also constituting the valve flap, between the longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto. Folding outwardly the first corner flap and the bottom flap parts situated beside thelongitudinal incision about a folding line extending in the tubular foil part next to the end point of the incision to form a bottom square with the first corner flap and a second corner flap. Folding inwardly the bottom flaps about a cross folding line while inserting a partition means which at least partially has a width corresponding with the distance between the eventual folding edges. Forming first sealed joints to connect the bottom flapfparts and second sealed joints to connect the first angular flap part,

In this known method the partition member consists of a flat plate-shaped body of uniform width and thickness, the member being provided with sealing members. The stamp applied on the outer side to the turned over bottom valve parts carries likewise sealing members which are opposite each other when the stamp and the partition member are lying on eachother so that a sealing effect is applied from both sides. In this way it is possible to manufacture extraordinary good bags from tubular foil with a rather great thickness of wall,

especially valve bags, which are used for packing fertilizer and like substances.

, In order to attain the object of the invention the partition member provided under the bottom valves has, at least over the effective length of the second sealed joints to be formed connecting the valve flap with the bottom flaps and which is next to the end of the flap On the other hand, the height of the partition member is so selected that the totalcircumference of a cross section through the partition member is always constant. The second sealed joints are provided in such a way that in the finished bottom their shortest distance is at least equal to the distance between the edges to be turned over in the part next to the valve flap. After the partition member has been removed, the valve flap part is stretched under the bottom part formed by the bottom flaps and when forces are exerted on the valve flap from within the bag this valve part will tend to contact the bottom formed by the bottom flap parts.

The invention relates likewise to a device for performing the method which comprises at least one partition member and a sealing stamp cooperating therewith. The partition member arid/or the sealing stamp have first and second sealing members opposite each other, The partition member over a raised part has a smaller width, while on the other hand the height and shape in the area of this smaller width is selected in such a way that the circumference of a cross section of the partition member is always equal to the circumference of the cross section in the wider part of the partition member. The second sealing members for sealing together the valve flap and the tubular foil body on the partition member are provided in such a way that their smallest distance measured over the circumference of the partition member is at least equal to the half circumference of the partition member in its widest area.

The invention is hereinafter clarified with reference to the drawings in which an embodiment is represented.

In the drawings:

FIG. 1 shows a flattened tubular foil part used for manufacturing a plastic bag;

FIG. 2 shows in a reduced scale a tubular foil part according to FIG. 1 in a folded condition;

FIG. 3 represents a bag with finished bottom;

FIG. 4 is a perspective view of a partition member applied in order to obtain a bottom of a plastic bag accofding to FIG. 3; and

FIG. 5 is a perspective view of a block bag provided with a valve of a more flexible foil than the foil of the bag.

FIG. ll illustrates a flattened tubular foil part 1 with longitudinal edges 2 and 3 and front and back walls 4,5 respectively. From one end of the tubular foil 1 a first longitudinal incision 6 is made to form a first inner corner flap 7, which also constitutes the valve flap, between the longitudinal incision 6 and the longitudinal edge 2 of the tubular foil situated closest thereto. On the other side of the longitudinal incision 6 are bottom flaps 8 and 8'. These bottom flaps have a length shorter than the first corner flap 7, 7.

In the tubular foil part 1 a second longitudinal incision 9 is made, which extends parallel to the longitudinal edge 3 of the foil, whereby a second corner flap 10 is formed. This second corner flap 10 has a length shorter than that of the bottom flaps 8 and 8'. The first longitudinal incision 6 and the second longitudinal incision 9 end in end points 11, 11 and l2, 12'. These end points 11, 11' and 12, 12 of the incisions can be connected by a line extending perpendicularly to the longitudinal edges 2 and 3 of the tubular foil. The part of the tubular foil which comprises the first comer flap 7, 7', the bottom flaps 8, 8' and the second corner flap l0, 10' is unfolded about a folding line 13 extending in the area next to the end points 11, 11', l2, 12' of the incisions. In this way a bottom square with a first corner flap 7 and a second corner flap 10 is formed. The bottom flaps 8, 8' are subsequently folded inwardly while forming folding edges 14a, 14b which extend perpendicularly to the longitudinal foil edges 2 and 3. These folding edges of the bottom flap parts extend also in the area between the initial folding line 13 and a line extending through the end points 11, 11' of the incision, which line is perpendicular to the longitudinal edges 2 and 3 of the tubular foil.

The parts of the bottom flaps 8, 8 which are folded over each other are interconnected by first sealed joints a, 15b, while the second corner flap 10 is connected to the bottom flaps 8, 8' by means of sealed joints 16a, 16b, 16c.

Sealed joints 17a, 17b are formed to connect the valve flap part 18, formed by the bottom flap 7, with the bottom flaps 8, 8'. The sealed joints 17a, 17b are formed in such a way that the distance between these sealed joints is at least equal to the distance between the side edges 14a, 14b formed by the inwardly folded bottom flap parts.

When a fiat partition member is used within the bag to form the first sealed joints 15a, 15b, the sealed joints 16a, 16b and 160 and the second sealed joints 17a, 17b, because of the thickness of the partition member it is almost impossible to form the sealed joints on or in the vicinity of the final folding edges 14a, 14b of the bottom flaps formed on folding the latter. This is possible by using a partition member as represented in FIG. 4. This partition member is provided with second sealing members 19 for forming the second sealed joints 17a, 17b and first sealing members 20 for forming the first sealed joints 15a, 15b to connect the bottom flaps.

As can be seen, the width b of the partition member increases in the direction of the end carrying a triangular end part; the greatest width being at about the location where the part 21a of the partition member is connected with the triangular part 21b of the partition member. It may be seen that the beginning of the part 21a of the partition member is raised. The circumference of a cross section at an arbitrary point on the partition member is, however, always such that the circumference of this cross section is almost equal to the circumference of the cross section of the part 210 of the partition member in its widest part which is situated between the points 22a and 22b.

In order to ensure that after removal of the partition member the second sealed joints 17a, 17b are positioned almost exactly on the eventually formed folding edges of the corner flaps 8, 8' it is necessary that the distance of the two second sealing members 19 measured on the surface of the partition member is substantially at least equal to the distance between the end points 22a and 22b of the first partition member part 210. The endpoints 22a, 22b are situated on the connecting line between a first part 21a and a second part 21b of the partition member.

After folding the bottom flaps and associated corner flap parts, a sealing stamp (not shown) adapted to the partition member is applied thereto. This sealing stamp likewise carries first and second sealing members, which in the effective position lie opposite the first sealing members, 20 and second sealing members 19, and the sealing members 23a, 23b and 23c for forming the sealed joints 16a, 16b and 160.

It is obvious that due to the application of such a partition member the sealed joint can be easily formed in the part which will constitute the eventual folding edges of the bottom flaps.

It has been found that in this way a securing of the valve is obtained which ensures that the valve flap 18, when the bag has been filled, will lie against the bottom formed by the bottom flaps 8, 8' because of the weight of the contents of the bag. In this way a faultless closure of the bags is obtained. It has also been found that due to the simultaneous effect of sealing heat from the outer side and from the inner side on the foil parts to be connected an exceptionally firm sealed joint is obtained, while on the other hand the manner in which the valve flap 18 is secured ensures an absolutely dependable sealing.

In particular cases it is advisable to subject the free edge 24 of the bottom flaps 8, 8, which are sealed to each other, to an additional thermal treatment, e.g., when the sealed joints are formed, whereby a beaded edge is obtained which ensures an easier introduction of the nozzles of the filling machines into such valve bags, moreover, it is possible to subject the triangular part 25a, indicated in FIG. 3, at the folding line 14 to an additional sealing treatment which contributes to a proper introduction of the nozzle into the plastic bag. It depends from case to case, however, whether this measure will be used or not. An analogous sealing together of the parts in the triangular part 250 will then also be effected in a triangular part 25b.

According to a preferred embodiment free ends of the sealed joints are in the shape of rounded off seals. Such a rounded off free end 28 at the end of the sealed joints 17a and 17b is shown in FIG. 5. The rounded off free ends 28 are situated at the end edge 26 of the valve flap 7, 7'. In order to obtain the rounded off free ends the sealing members 19 are provided with rounded off ends 27. Similar rounded off ends 29 can be obtained by means of sealing members 23a. In this way any tearing of the bag at the seal is prevented.

Still another embodiment is shown in FIG. 5, wherein the first corner flap 7, 7' constituting the valve of the bag is connected with an auxiliary flap 31 of relatively flexible thin thermoplastic material. This flexible material is thinner than corner fiap 7, 7'. The connection is obtained by placing the thin foil 31 under the first corner flap 7, 7, the flap 31 being positioned such that the short edges 32 of the flap 31 almost coincide with the free edges 33 of the flaps 8, 8. After folding of the bottom flaps 8, 8' inwardly along the folding edges 14 and 14', the flap 31 is connected with the corner flap 7, 7 by means of heat selas 36. These heat seals prevent displacement and tearing off of the flap 31.

Furthermore, seals 37 are provided in the region parallel to the folding edges l4, 14 in order to connect the longitudinal edges 32 with the bottom flaps 8, 8'. The provision of the thinner flap 31 (e.g., having half of the thickness of the foil material constituting the first corner flap 7, 7') ensures a reliable closure of the valve which is not always the case with the first corner flaps 7, 7 It is preferred to apply rounded seal ends in the region of inner end edge 26 of flap 31 and preferable also in the region of inner end edge 38 of first corner flap 7, 7'.

The edges 35 form the entrance of the valve.

It will be obvious that the flap 31 is connected with the bag during manufacture of the bottom seals of the bag.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions, and accordingly, it is desired to comprehend such modifications within this invention as may fall within the scope of the appended claims.

What is claimed is:

l. A plastic block bag with a filling valve obtained from a tubular foil part by making at least one longitudinal incision at one end of each tubular foil while forming a first inner corner flap part constituting a valve flap between the longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto, folding outwards the first flap and folding bottom flap parts situated beside the longitudinal incision about a folding line extending in the area next to the end points of said incision while forminga bottom square with said first corner flap and a second corner flap, folding inwards the bottom flaps about a transverse folding line and forming first sealed joints for connecting the bottom flap parts and forming second sealed joints for connecting the first corner flap part, constituting the valve flap, with the bottom flaps, the arrangement being such that the folding edges of the bottom flap parts extend, when the bottom is flat, perpendicularly to the longitudinal edges of the tubular foil in the area between the initial folding line and a line extending through the end point of incision almost perpendicularly to the longitudinal edges of the tubular foil, whereby in the flattened condition of the bottom and the tubular foil constituting the bag, the distance between the second sealed joints is at least equal to the distance between the folding edges of the bottom flat constituting the finished bottom square, said distances being measured over the outer surface of the bottom square bearing the first sealed joints connecting bottom flap parts, said valve flap being stretched upon filling of the bag.

smaller thickness than the foil material of the bag. 

1. A plastic block bag with a filling valve obtained from a tubular foil part by making at least one longitudinal incision at one end of each tubular foil while forming a first inner corner flap part constituting a valve flap between the longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto, folding outwards the first flap and folding bottom flap parts situated beside the longitudinal incision about a folding line extending in the area next to the end points of said incision while forming a bottom square with said first corner flap and a second corner flap, folding inwards the bottom flaps about a transverse folding line and forming first sealed joints for connecting the bottom flap parts and forming second sealed joints for connecting the first corner flap part, constituting the valve flap, with the bottom flaps, the arrangement being such that the folding edges of the bottom flap parts extend, when the bottom is flat, perpendicularly to the longitudinal edges of the tubular foil in the area between the initial folding line and a line extending through the end point of incision almost perpendicularly to the longitudinal edges of the tubular foil, whereby in the flattened condition of the bottom and the tubular foil constituting the bag, the distance between the second sealed joints is at least equal to the distance between the folding edges of the bottom flap constituting the finished bottom square, said distances being measured over the outer surface of the bottom square bearing the first sealed joints connecting the bottom flap parts, said valve flap being stretched upon filling of the bag.
 2. A plastic block bag according to claim 1, wherein the sealed joints are formed due to the effect of heat on either side of the foil parts to be interconnected.
 3. A plastic block bag according to claim 1, wherein the free edge of the bottom flap parts which are sealed together constitutes a beaded edge.
 4. A plastic block bag according to claim 1, wherein the valve is provided with an auxiliary valve flap of a smaller thickness than the foil material of the bag. 